• Posted November 29, 2022

Healthy Plant-Based Diets Lower Men's Odds for Colon Cancer

Are you an older man worried about your risk for colon cancer? Eating whole grains, vegetables, fruits and legumes may improve your odds of dodging the disease, new research shows.

"Although previous research has suggested that plant-based diets may play a role in preventing colorectal cancer, the impact of plant foods' nutritional quality on this association has been unclear," said study co-author Jihye Kim, from Kyung Hee University in South Korea, "Our findings suggest that eating a healthy plant-based diet is associated with a reduced risk of colorectal cancer."

Kim noted that colon cancer is the third most common cancer worldwide and that a man has a lifetime odds for developing it of one in 23. A woman has a lifetime risk of one in 25.

The new report was published online Nov. 29 in BMC Medicine.

The researchers studied a population of nearly 80,000 American men, finding that those who ate the highest average daily amounts of healthy plant-based foods had a 22% lower risk of colon cancer compared to those who ate the lowest amounts of these foods.

While studying more than 93,000 American women, the researchers did not find the same association.

"We speculate that the antioxidants found in foods such as fruits, vegetables and whole grains could contribute to lowering colorectal cancer risk by suppressing chronic inflammation, which can lead to cancer,"Kim said in a journal news release.

"As men tend to have a higher risk of colorectal cancer than women, we propose that this could help explain why eating greater amounts of healthy plant-based foods was associated with reduced colorectal cancer risk in men, but not women,"Kim added.

The risk also varied by race. While colon cancer risk was 20% lower in Japanese American men who ate the most plant foods compared to those who ate the least plant foods, it was 24% lower in white men who ate the highest amounts of these healthy foods compared to those of the same race who ate the least.

No significant associations were found between plant-based diets and colon cancer in Black, Hispanic or Native Hawaiian men. This could be because of other cancer risk factors that exist in those groups, the study authors suggested.

The data came from a multiethnic survey among adults recruited from Hawaii and Los Angeles between 1993 and 1996. About 30% of male participants were Japanese American, 26% were white, 24% were Hispanic, 13% were Black and 7% were Native Hawaiian.

Study participants reported their usual food and drink intake during the previous year. The researchers evaluated that intake based on healthy and unhealthy plant foods, then calculated the incidence of new colon cancer cases until 2017 using data from cancer registries.

The investigators accounted for other factors, such as age, family history of colon cancer, body mass index (based on height and weight), smoking history, physical activity levels, alcohol consumption, multivitamin use, daily energy intake and, for women, use of hormone replacement therapy. Nearly 5,000 participants (2.9%) developed colon cancer during the study period.

The study was observational and could not prove a cause-and-effect relationship. It also did not account for the beneficial effects of fish and dairy on colon cancer. It's also not known for how long participants adhered to their recorded diets.

Future research is needed to investigate genetic and environmental factors that may influence the association between plant-based food intake and colon cancer between racial and ethnic groups, the authors said.

More information

The American Cancer Society has more on colon cancer.

SOURCE: BMC Medicine, news release, Nov. 29, 2022